Journal Club Update: Nystagmus and Saccadic Intrusions

Nystagmus is common, with a prevalence of approximately 24 per 10,000 in the general population. Because of the associated visual symptoms and negative impact on quality of life, many patients with nystagmus request treatment. Unlike physiologic nystagmus (e.g., during head movements), where slow phase drifts minimize retinal image slip, the slow phase drifts of pathologic nystagmus cause retinal image slip. When retinal image slip from pathologic slow phase drifts is greater than about 5 degrees per second, it can produce blurred vision, because the image of the object of interest no longer lies on the fovea, and illusory motion of the visual environment (oscillopsia).3 Saccadic intrusions also cause visual symptoms, such as difficulty reading, as they consist of inappropriate saccadic eye movements that take the image of the object of interest off the fovea.